I have the Klipsch Image S-4 in ear headphones and they work great. I got them off ebay for a good price.
I wear them to the gym, around town and always have them in when I work. I plant trees so they are in the woods Monday to Friday, rain or shine they work great. I have had them in while it rained all day and they have never quit on me. They are over a year old, close to two years going strong.
The sound is awesome to me, clear and you can hear things otherwise unheard with other headphones. And they are really light and comfortable to wear. I have mine in for 9 hours straight at work and don't even notice them.
Forgot to mention that they are noise cancelling. Don't have to have the volume very high which is nice, ipod lasts a lot longer.